Camera

ABSTRACT

A mirror contact member includes a first eccentric portion that is eccentric with respect to a rotation center of the mirror contact member, and a second eccentric portion that is eccentric with respect to the rotation center of the mirror contact member substantially at the same eccentricity as that of the first eccentric portion. When a mirror is displaced to a mirror-down state, the mirror is contacted with the first eccentric portion. A bounce regulation member is disposed to be rotatable about the second eccentric portion.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a camera such as a single-lens reflexcamera, and more particularly to a camera including a mechanism thatsuppresses a bounce (rebound) of a rotatable mirror.

2. Description of the Related Art

A single-lens reflex camera includes a main mirror for reflecting lightfrom an object and introducing the reflected light to an optical systemof a finder, and a sub-mirror for introducing the light having passedthrough the main mirror to a focus detector. The main mirror and thesub-mirror are displaceable to a mirror-down state where both themirrors are positioned in an optical path for photographing, and to amirror-up state where both the mirrors are retracted away from theoptical path for photographing.

When the main mirror and the sub-mirror are displaced to the mirror-downstate, the main mirror and the sub-mirror strike against a stopperdisposed on a mirror box, whereby the main mirror and the sub-mirror arecaused to bounce (rebound off the stopper). A finder image can bestabilized by suppressing the bounce of the main mirror. Further, afocus detecting operation can be started earlier by suppressing thebounce of the sub-mirror.

Japanese Patent Laid-Open No. 9-203972 discloses the followingtechnique.

A main mirror 1 and a main-mirror holding frame 2 are displaced to amirror-down state and strike against a main-mirror receiving member 29that is in an observing position. Upon the main mirror 1 and themain-mirror holding frame 2 striking against the main-mirror receivingmember 29, an inertial brake plate 21 and the main-mirror receivingmember 29 are rotated. In conjunction with the rotation of the inertialbrake plate 21 and the main-mirror receiving member 29, a sub-mirrorretaining member 31 is rotated to come into a bounce locus of asub-mirror 11. As a result, a sub-mirror retainer 32 of the sub-mirrorretaining member 31 contacts with the sub-mirror 11 and reduces thebounce thereof.

SUMMARY OF THE INVENTION

With the technique disclosed in Japanese Patent Laid-Open No. 9-203972,when the main mirror 1 and the main-mirror holding frame 2 strikeagainst the main-mirror receiving member 29, the momentum of the mainmirror 1 and the main-mirror holding frame 2 is transferred to theinertial brake plate 21 and the main-mirror receiving member 29.

In Japanese Patent Laid-Open No. 9-203972, however, the sub-mirror doesnot include such a bounce suppression mechanism as that provided for themain mirror, and a bounce range of the sub-mirror is just restricted.Further, when a mirror-down position of the mirror is adjusted, themirror bounce range is changed.

An embodiment of the present invention provides a camera including amirror, a mirror contact member with which the mirror is contactable,and a bounce regulation member including a bounce regulation portionwith which the mirror is contacted when the mirror is bounced from themirror contact member, wherein the mirror contact member is rotatablyprovided so as to be rotatable around a rotation center, wherein themirror contact member includes a first eccentric portion that iseccentric with respect to the rotation center of the mirror contactmember, and a second eccentric portion that is eccentric with respect tothe rotation center of the mirror contact member substantially at thesame eccentricity as that of the first eccentric portion, wherein whenthe mirror is displaced to a mirror-down state, the mirror is contactedwith the first eccentric portion, and wherein the bounce regulationmember is disposed to be rotatable about the second eccentric portion.

According to the embodiment of the present invention, there can beobtained the camera including a mirror driving mechanism in which themirror bounce range is not changed when the mirror-down position of themirror is adjusted.

Further features of the present invention will become apparent from thefollowing description of exemplary embodiments with reference to theattached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view illustrating the overall construction of acamera according to an embodiment of the present invention.

FIGS. 2A to 2C are explanatory views to explain the operation of amirror driving mechanism.

FIG. 3 is a chart to explain a mirror driving sequence.

FIG. 4 is an explanatory view illustrating the constructions of a mainmirror balancer and a sub-mirror balancer.

FIGS. 5A and 5B are explanatory views to explain the operations of themain mirror balancer and the sub-mirror balancer.

FIG. 6 is an exploded perspective view illustrating a sub-mirrorbalancer mechanism on the left side of a sub-mirror frame.

FIG. 7 is an explanatory view to explain the operation of the sub-mirrorbalancer mechanism on the left side of the sub-mirror frame.

FIGS. 8A and 8B are explanatory views to explain the operation of thesub-mirror balancer mechanism on the left side of the sub-mirror frame.

FIG. 9 is a front view of a shutter device.

FIGS. 10A to 10C are explanatory views illustrating the detailedstructure of a mirror box.

DESCRIPTION OF THE EMBODIMENTS

A camera according to an embodiment of the present invention will bedescribed below with reference to the drawings. The camera according tothis embodiment is practiced as a single-lens reflex still camera usinga silver halide film, or as a single-lens reflex digital camera using aCCD sensor or a MOS-type solid-state image pickup element.

FIG. 1 is a schematic view illustrating the inner overall constructionof the single-lens reflex digital camera according to the embodiment.

In FIG. 1, a photographing lens 10 is detachably attached to a body ofthe digital camera. An object image is focused on an image plane by thephotographing lens 10. The photographing lens 10 is constituted, thoughnot illustrated, by a lens driver, an aperture blade unit for exposurecontrol, an aperture driver for driving the aperture blade unit, etc.

A main mirror 100 is constituted as a half mirror. When the main mirror100 is in a mirror-down state, the main mirror 100 reflects the objectimage, which is focused by the photographing lens 10, toward a focusingscreen. At that time, the main mirror 100 allows a part of the objectimage to pass therethrough toward a sub-mirror 200. The sub-mirror 200reflects the part of the object image (light), having passed through themain mirror 100, toward a focus detector 11.

The main mirror 100 is driven by a mirror driving mechanism (describedlater) such that the main mirror 100 is displaced to either amirror-down state where it is positioned in an optical path of an objectlight flux, thereby introducing the object image to the focusing screen,or a mirror-up state where it is retracted away from the optical path ofthe object light flux, thereby introducing the object image to an imagepickup element 13.

The sub-mirror 200 is displaced in conjunction with the main mirror 100when the main mirror 100 is driven by the mirror driving mechanism(described later). More specifically, when the main mirror 100 is in themirror-down state, the sub-mirror 200 introduces (directs) the lightflux having passed through the main mirror 100 to the focus detector 11.On the other hand, when the main mirror 100 is in the mirror-up state,the sub-mirror 200 is retracted away from the optical path of the objectlight flux together with the main mirror 100.

A pentaprism 14 reflects the object image focused on the focusing screenafter converting it to a normal erect image.

An eyepiece lens 15 introduces, to the eye of a photographer, the objectimage that has been converted to the normal erect image and reflected bythe pentaprism 14.

A photometric device 16 measures the brightness of the object image,which has been focused on the focusing screen, through the pentaprism14. Exposure control during an exposure is performed in accordance withan output signal of the photometric device 16.

The focus detector 11 detects a defocus amount of the object image. Thelens driver for the photographing lens 10 is controlled in accordancewith an output signal of the focus detector 11, whereby focus adjustmentis performed.

The shutter device 12 mechanically controls the incidence of the objectlight flux on the image surface.

The image pickup element 13 picks up the object image focused by thephotographing lens 10 and converts it to electrical signals. Forexample, a two-dimensional image pickup device of the CCD or MOS type isused as the image pickup element 13.

The photographing operation in the digital camera according to thisembodiment will be described below.

Before the start of photographing, the object image incoming through thephotographing lens 10 is brought into a state where the photographer canconfirm the object image, directed by the main mirror 100 and thepentaprism 14, through the eyepiece lens 15. At that time, a part of theobject image enters the focus detector 11 through the sub-mirror 200.When the photographer operates a switch, the photographing lens 10 isdriven in accordance with information of the object distance detected bythe focus detector 11. In such a manner, focusing can be performed.Further, the photometric device 16 measures the object brightness,whereby a lens aperture value and a shutter exposure time aredetermined.

When photographing is performed with a release operation by thephotographer, the main mirror 100 and the sub-mirror 200 are retractedupwards away from the optical path for photographing and blades of theshutter device 12 are opened, thus causing the object image to enter theimage pickup element 13. After the elapse of a proper exposure time, theblades of the shutter device 12 are operated to close an opening of animage frame, and the main mirror 100 and the sub-mirror 200 are returnedinto the optical path for photographing. The photographing operation isthus completed.

The operation of the mirror driving mechanism will be described belowwith reference to FIGS. 2A to 2C.

FIG. 2A illustrates a standby state before release, i.e., a state aftercompletion of mirror-down and charge operations.

A base plate 300 mounting the mirror driving mechanism thereon includesa hole to which a rotation shaft 101 of the main mirror 100 is fitted,and an arc-shaped hole along which a drive shaft 102 of the main mirror100 is turned. A mirror-down spring 100Sp for biasing the main mirror100 in the down-direction is held against the drive shaft 102 of themain mirror 100.

A mirror lever 310 is rotated about a rotation center 310 d. A down-hooklever 340 is attached to the mirror lever 310. The down-hook lever 340is rotated about a rotation center 340 a. An attraction lever 370 and adetachment lever 360 are integral with each other and are both rotatedabout a rotation center 360 a of the detachment lever 360. An attractionportion 380 a attractable by an electromagnet 380 is fixed to a distalend of the attraction lever 370.

The electromagnet 380 includes a magnet, a coil, and a yoke. In anon-energized state, the attraction portion 380 a is held in closecontact with the yoke by a magnetic force. When the coil is energized,the magnetic force is canceled and the attraction portion 380 a isdetached away from the yoke.

A detachment spring 360Sp biases the attraction portion 380 a in thedirection in which the attraction portion 380 a is detached away fromthe yoke. In other words, the detachment spring 360Sp biases theattraction lever 370 in the direction in which the attraction lever 370is rotated about the rotation center 360 a of the detachment lever 360to the right as viewed in FIG. 2A. When the attraction portion 380 a isattracted to the yoke, the attraction portion 380 a is held at the yokeby a greater force than the biasing force of the detachment spring360Sp.

In the standby state before release, as illustrated in FIG. 2A, anup-hook lever 350 and an engagement portion 310 a of the mirror lever310 are engaged with each other. With that engagement, the mirror lever310 is kept in the state, illustrated in FIG. 2A, against the biasingforce of a mirror-up spring 310Sp. Further, in the state illustrated inFIG. 2A, the down-hook lever 340 and an engagement portion 320 a of amirror drive lever 320 are engaged with each other.

A mirror-up operation will be described below.

When a pulse is supplied to the electromagnet 380 in accordance with arelease signal, the attraction lever 370 fixed with the attractionportion 380 a and the detachment lever 360 integral with the attractionlever 370 are rotated left (counterclockwise) by the spring force of thedetachment spring 360Sp about the rotation center 360 a of thedetachment lever 360.

When the detachment lever 360 is rotated left, a roller 360 b of thedetachment lever 360 is contacted with a contact portion 350 b of theup-hook lever 350, whereupon the up-hook lever 350 is rotated left abouta rotation center 350 a. With the left rotation of the up-hook lever350, the engagement between the up-hook lever 350 and the engagementportion 310 a of the mirror lever 310 is disengaged.

When the engagement between the up-hook lever 350 and the engagementportion 310 a of the mirror lever 310 is disengaged, the mirror lever310 is rotated left about the rotation center 310 d by the spring forceof the mirror-up spring 310Sp. At that time, because the engagementportion 320 a of the mirror drive lever 320 is engaged with thedown-hook lever 340, the mirror drive lever 320 is rotated left aboutthe rotation center 310 d of the mirror lever 310. With the leftrotation of the mirror drive lever 320, a cam portion 320 b of themirror drive lever 320 pushes up the main mirror drive shaft 102,whereby the mirror-up operation is performed.

The spring force of the mirror-up spring 310Sp is sufficiently greaterthan that of the mirror-down spring 100Sp. Therefore, the mirror-upoperation can be performed at a high speed.

FIG. 2B illustrates a state after completion of the mirror-up operation.

An operation sensor 330 is fixed to the mirror drive lever 320, and thecompletion of the mirror-up operation is detected by an up-switch (UPSW)303 including a photo interrupter.

The mirror lever 310 includes an attraction cam portion 310 b. When themirror lever 310 is rotated left, the attraction cam portion 310 b iscontacted with a roller 360 c of the detachment lever 360, therebyrotating the detachment lever 360 right (clockwise) against the springforce of the detachment spring 360Sp. With the right rotation of thedetachment lever 360, the attraction portion 380 a in a state detachedfrom the electromagnet 380 is attracted to the electromagnet 380 again.

Further, because the engagement portion 320 a of the mirror drive lever320 is engaged with the down-hook lever 340, the down-hook lever 340 isrotated left about the rotation center 310 d of the mirror lever 310together with the mirror lever 310 and the mirror drive lever 320. Anunhook portion 340 b of the down-hook lever 340 is moved to a positionwhere the unhook portion 340 b is contactable with the roller 360 b ofthe detachment lever 360. After a bounce generated with the mirror-upoperation has settled, an exposure operation is performed, followingwhich the process advances to a mirror-down step.

The mirror-down operation will be described below.

When a pulse is supplied to the electromagnet 380 in the mirror-up stateof FIG. 2B, the attraction lever 370 and the detachment lever 360 bothassociated with the attraction portion 380 a are rotated left(counterclockwise) by the spring force of the detachment spring 360Sp.

When the detachment lever 360 is rotated left, the roller 360 b of thedetachment lever 360 is contacted with the unhook portion 340 b of thedown-hook lever 340, and the down-hook lever 340 is rotated right(clockwise) about the rotation center 340 a. With the right rotation ofthe down-hook lever 340, the engagement between the down-hook lever 340and the engagement portion 320 a of the mirror drive lever 320 isdisengaged. When the engagement between the down-hook lever 340 and theengagement portion 320 a of the mirror drive lever 320 is disengaged,the spring force of the mirror down-spring 100Sp is caused to act on themain mirror drive shaft 102. As a result, the mirror drive lever 320 isrotated right about the rotation center 310 d of the mirror lever 310.

FIG. 2C illustrates a state after completion of the mirror-downoperation.

A main mirror balancer 400 is disposed on the base plate 300 of themirror box. When the main mirror 100 is contacted with the main mirrorbalancer 400, the main mirror balancer 400 is rotated right against thespring force of a main mirror balancer spring 400Sp, thereby damping ashock generated with the mirror-down operation of the main mirror 100.In addition, the main mirror balancer 400 strikes against a damper 302at a fore end of the main mirror balancer 400 when it is rotated right,thereby further damping the shock imposed on the main mirror balancer400.

A sub-mirror balancer 500 is disposed on the base plate 300 of themirror box. When the sub-mirror 200 is contacted with the sub-mirrorbalancer 500, the sub-mirror balancer 500 is rotated right against thespring force of a sub-mirror balancer spring 500Sp (see FIGS. 5A and 6),thereby damping a shock generated with the mirror-down operation of thesub-mirror 200.

A mirror charge operation will be described below.

A roller 310 c disposed in a charge portion of the mirror lever 310 ispressed to the left by a charge lever (not illustrated) in the state ofFIG. 2C, whereby the mirror lever 310 is rotated right about therotation center 310 d of the mirror lever 310 against the spring forceof the mirror-up spring 310Sp. With the right rotation of the mirrorlever 310, the attraction cam portion 310 b of the mirror lever 310 iscontacted with the roller 360 c of the detachment lever 360, whereby thedetachment lever 360 is rotated right against the spring force of thedetachment spring 360Sp.

With the right rotation of the detachment lever 360, the attractionlever 370 is also rotated right and the attraction portion 380 a in thedetached state is attracted to the electromagnet 380 again.

When the mirror lever 310 is rotated right in the state of FIG. 2C, thedown-hook lever 340 is engaged with the engagement portion 320 a of themirror drive lever 320, and the up-hook lever 350 is engaged with theengagement portion 310 a of the mirror lever 310. As a result, themirror charge operation is completed and the mirror driving mechanism isreturned to the state of FIG. 2A.

While in this embodiment, as described above, the electromagnet isutilized as a trigger for starting the mirror-up operation and themirror-down operation and the springs are used as driving sources forthe mirror-up operation and the mirror-down operation, the mirrordriving mechanism is not limited to the above-described arrangement. Forexample, an electromagnetic motor, a stepping motor, or an ultrasonicmotor may also be used as the driving source in the mirror drivingmechanism.

However, when the electromagnetic motor is used to perform the mirroroperation, the operation start time tends to vary due to, e.g., theinertia and the temperature characteristic of the motor. Further, aspeed reduction mechanism is required and a mechanical delay time occursin transmission of a driving force. For that reason, it is suitable, asin the above-described embodiment, to employ the electromagnet as thetrigger and to utilize the spring force for performing the mirroroperation in the mirror driving mechanism that requires a high speed andhigh accuracy.

FIG. 3 is a chart to explain a mirror driving sequence in the cameraaccording to this embodiment. In the mirror driving sequence in thecamera according to this embodiment, as illustrated in FIG. 3, a chargeoperation is started before the completion of the mirror-down operation.Even during arithmetic operations for AF (auto-focusing) and AE(auto-exposure), therefore, the charge operation can be continuedregardless of accuracy in stopping the mirror. Further, a variation inthe charge operation does not affect the mirror operating speed and thearithmetic operation times for AF and AE. An influence of such avariation upon continuous shooting is also small.

The constructions of the main mirror balancers 400 and 410 and thesub-mirror balancers 500 and 510 will be described below with referenceto FIGS. 4, 5A and 5B.

A main mirror frame 100 a for holding the main mirror 100 has hingeshaft portions (rotation shafts) 101, which are formed respectively atthe left and right sides of the main mirror frame 100 a and which serveas rotation centers. A drive shaft 102 for rotating the main mirror 100is formed at one side of the main mirror frame 100 a. Contact plates 103and 104 formed by members separate from the main mirror frame 100 a aredisposed respectively at left and right distal ends of the main mirror100.

The main mirror frame 100 a is made of a light material, such asaluminum or resin, in many cases to reduce the inertia moment. If thecontact plates 103 and 104 are made of the same material as that of themain mirror frame 100 a, durability of the contact plates 103 and 104may deteriorate. For that reason, the contact plates 103 and 104 aremade of a material, such as stainless steel, having higher strength thanthe material of the main mirror frame 100 a, or formed of rubber membershaving a shock absorbing ability.

As illustrated in FIGS. 4 and 5A, the main mirror balancer 400 isdisposed on the left side (one side) of the main mirror frame 100 a. Themain mirror balancer 400 includes a shaft portion 401 serving as arotation center, a contact shaft 402, a main-mirror angle adjustingportion 403, and a balancer weight 404 made of a material having a largemass, such as brass.

As illustrated in FIGS. 4 and 5B, the main mirror balancer 410 isdisposed on the right side (other side) of the main mirror frame 100 a.The main mirror balancer 410 includes a shaft portion 411 serving as arotation center, a contact shaft 412, a main-mirror angle adjustingportion 413, and a balancer weight 414 made of a material having a largemass, such as brass.

In the mirror-down state, the main-mirror angle adjusting portion 403 iscontacted with an adjustment member 301 by the spring force of thespring 400Sp. Further, the state where the contact plate 103 of the mainmirror 100 is contacted with the contact shaft 402 is held by the springforce of the mirror-down spring 100Sp. Similarly, in the mirror-downstate, the main-mirror angle adjusting portion 413 is contacted with anadjustment member 420 by the spring force of a spring 410Sp. Further,the state where the contact plate 104 of the main mirror 100 iscontacted with the contact shaft 412 is held by the spring force of themirror-down spring 100Sp.

The adjustment member 301 has an eccentric shaft. By rotating theadjustment member 301 with a tool, therefore, the main mirror balancer400 is rotated about the shaft portion 401, whereby a contact positionbetween the contact shaft 402 and the contact plate 103 of the mainmirror 100 is changed.

Similarly, the adjustment member 420 has an eccentric shaft. By rotatingthe adjustment member 420 with a tool, therefore, the main mirrorbalancer 410 is rotated about the shaft portion 411, whereby a contactposition between the contact shaft 412 and the contact plate 104 of themain mirror 100 is changed.

In such a way, an angle of the main mirror frame 100 a about the hingeshaft portions 101 and an inclination of the main mirror frame 100 a inthe left-and-right direction can be adjusted.

The sub-mirror 200 is held by a sub-mirror frame 200 a such that thesub-mirror 200 is rotatable about rotation centers at side surfaces ofthe main mirror frame 100 a. Contact portions 201 and 202 are formedrespectively at the left and right sides of the sub-mirror frame 200 a.

As illustrated in FIGS. 4 and 5A, the sub-mirror balancer 500 isdisposed on the left side (one side) of the sub-mirror frame 200 a. Thesub-mirror balancer 500 includes a shaft portion 501 serving as arotation center for the sub-mirror balancer 500, a contact shaft 502, anadjustment portion 503, and a sub-mirror lock lever 504 provided with alock pin 505. The contact shaft 502 functions as a mirror contactmember, the sub-mirror lock lever 504 functions as a bounce regulationmember, and the sub-mirror balancer 500 functions as a rotation member.

In the mirror-down state, the adjustment portion 503 of the sub-mirrorbalancer 500 is contacted with an adjustment member 313 by the springforce of the spring 500Sp. The spring 500Sp functions as a biasingmember. A state where the contact portion 201 of the sub-mirror frame200 a is contacted with the contact shaft 502 is held by the springforce of a sub-mirror spring (not illustrated).

As illustrated in FIGS. 4 and 5B, the sub-mirror balancer 510 isdisposed on the right side (other side) of the sub-mirror frame 200 a.The sub-mirror balancer 510 includes a shaft portion 511 serving as arotation center for the sub-mirror balancer 510, a contact shaft 512, anadjustment portion 513, and a sub-mirror lock lever 514 provided with alock pin 515. The contact shaft 512 functions as the mirror contactmember, the sub-mirror lock lever 514 functions as the bounce regulationmember, and the sub-mirror balancer 510 functions as the rotationmember.

In the mirror-down state, the adjustment portion 513 of the sub-mirrorbalancer 510 is contacted with an adjustment member 520 by the springforce of a spring 510Sp. The spring 510Sp functions as the biasingmember. A state where the contact portion 202 of the sub-mirror frame200 a is contacted with the contact shaft 512 is held by the biasingforce of a sub-mirror spring (not illustrated).

In the balancer mechanism on the left side of the sub-mirror frame 200 aillustrated in FIGS. 4 and 5A, the contact shaft 502 contacting with thecontact portion 201 of the sub-mirror frame 200 a has an eccentricshaft. Stated another way, the contact shaft 502 is rotatably mounted tothe sub-mirror balancer 500, but a rotation center of the contact shaft502 is offset from a center of an outer periphery 502 a (see FIG. 6)thereof. So in particular the radius (distance) of the outer periphery502 a from the rotation center varies such that the maximum radius onone side is longer than the maximum radius on the opposite side.

Accordingly, by rotating the contact shaft 502 relative to thesub-mirror balancer 500, a contact position between the outer periphery502 a of the contact shaft 502 and the contact portion 201 of thesub-mirror frame 200 a is changed. With such a mechanism, an angle ofthe sub-mirror 200 in the mirror-down state can be adjusted.

Further, the sub-mirror lock lever 504 is rotatable relative to acylindrical portion 502 b (see FIG. 6) of the contact shaft 502. As inthe outer periphery 502 a of the contact shaft 502, the cylindricalportion 502 b is eccentric relative to the rotation center of thecontact shaft 502. The outer periphery 502 a of the contact shaft 502functions as a first eccentric portion, and the cylindrical portion 502b of the contact shaft 502 functions as a second eccentric portion.

Therefore, even when the angle of the sub-mirror 200 is adjusted byrotating the contact shaft 502 relative to the sub-mirror balancer 500,the size of a gap in which the bounce of the sub-mirror 200 is to besettled is not changed. In other words, a bounce regulation range is notchanged depending on the mirror-down position of the sub-mirror 200.

In the balancer mechanism on the right side of the sub-mirror frame 200a illustrated in FIGS. 4 and 5B, the contact shaft 512 contacting withthe contact portion 202 of the sub-mirror frame 200 a is formed as ashaft that is not rotatable relative to the sub-mirror balancer 510. Theadjustment member 520 has an eccentric cylindrical portion 520 a that iseccentric relative to the rotation center of the adjustment member 520.The adjustment portion 513 of the sub-mirror balancer 510 is contactedwith the eccentric cylindrical portion 520 a.

Accordingly, by rotating the adjustment member 520, the sub-mirrorbalancer 510 is rotated about the shaft portion 511, and a contactposition between the contact shaft 512 and the contact portion 202 ofthe sub-mirror frame 200 a is changed. With such a mechanism, the angleof the sub-mirror 200 in the mirror-down state can be adjusted.

Further, the sub-mirror lock lever 514 is rotatable relative to thecontact shaft 512. Therefore, even when the contact position between thecontact (positioning) shaft 512 and the contact (positioning) portion202 of the sub-mirror frame 200 a is changed by rotating the adjustmentmember 520, the size of a gap between the lock pin 515 and the contactportion 202 of the sub-mirror frame 200 a is not changed.

Thus, even when the angle of the sub-mirror 200 is adjusted by rotatingthe adjustment member 520, the size of a gap in which the bounce of thesub-mirror 200 is to be settled is not changed. In other words, thebounce state is not changed depending on the mirror-down position of thesub-mirror 200.

In this embodiment, the balancer mechanisms on the left side and theright side of the main mirror 100 and the sub-mirror 200 differ inconstruction and shape from each other. The balancer mechanism on theright side of the sub-mirror frame 200 a in this embodiment may beprovided on the left side of the sub-mirror frame 200 a, and thebalancer mechanism on the left side of the sub-mirror frame 200 a inthis embodiment may be provided on the right side of the sub-mirrorframe 200 a.

Further, in this embodiment, the shaft portion 401 serving as a rotationshaft of the main mirror balancer 400 and the shaft portion 411 servingas a rotation shaft of the main mirror balancer 410 are arranged incoaxial relation. Stated another way, the main mirror balancer 400 andthe main mirror balancer 410 are arranged such that the shaft portion401 and the shaft portion 411 are coaxially positioned.

The shaft portion 501 serving as a rotation shaft of the sub-mirrorbalancer 500 and the shaft portion 511 serving as a rotation shaft ofthe sub-mirror balancer 510 are arranged in coaxial relation. Statedanother way, the sub-mirror balancer 500 and the sub-mirror balancer 510are arranged such that the shaft portion 501 and the shaft portion 511are coaxially positioned.

With such an arrangement, it is easier to design the mirror drivingmechanism such that the inertia moments of the main mirror balancers 400and 410 on the left and right sides of the main mirror 100 are equal toeach other. It is also easier to design the mirror driving mechanismsuch that the inertia moments on the left and right sides of thesub-mirror balancers 500 and 510 are equal to each other.

Moreover, even when the inertia moments of both the main mirrorbalancers on the left and right sides of the main mirror 100 are madedifferent from each other, or when the inertia moments of both thesub-mirror balancers on the left and right sides of the sub-mirror 200are made different from each other, the difference between the inertiamoments can be easily confirmed.

FIG. 6 is an exploded perspective view illustrating details of thebalancer mechanism on the left side of the sub-mirror frame 200 a inFIG. 4.

The contact shaft 502 includes the (eccentric) outer periphery 502 athat is contacted with the contact portion 201 of the sub-mirror frame200 a, and the (eccentric) cylindrical portion 502 b that is insertedthrough an engagement hole 504 a of the sub-mirror lock lever 504. Aneccentricity of the outer periphery 502 a with respect to the rotationcenter of the contact shaft 502 is substantially equal to that of thecylindrical portion 502 b of the contact shaft 502 with respect to therotation center of the contact shaft 502. So the variation in radius,from the rotation center, of the outer periphery 502 a is substantiallythe same as the variation in radius, from the rotation center, of thecylindrical portion 502 b such that the point of maximum radius from therotation center on the outer periphery 502 a and the point of maximumradius from the rotation center on the cylindrical portion 502 b arealigned in the direction of the rotation axis. So in the particularembodiment the outer periphery 502 a and the cylindrical portion 502 bare preferably both coaxially mounted cylindrical portions, havingsubstantially the same diameter, with the offset of the rotation centerfrom the geometric center being substantially the same for each portion.

As illustrated in FIG. 6, the sub-mirror lock lever 504, a washer W1,the sub-mirror balancer 500, and a washer W2 are successively attachedto the contact shaft 502, and a distal end of the contact shaft 502 iscrimped. Accordingly, the sub-mirror lock lever 504 is held between thecontact shaft 502 and the sub-mirror balancer 500. In that state, thecylindrical portion 502 b of the contact shaft 502 is contacted with aninner peripheral surface of the engagement hole 504 a of the sub-mirrorlock lever 504.

Since the washer W1 is arranged between the sub-mirror lock lever 504and the sub-mirror balancer 500, the sub-mirror lock lever 504 issmoothly rotatable about the cylindrical portion 502 b. Further, sincethe washer W2 is arranged on the right side of the sub-mirror balancer500 as viewed in FIG. 6, the contact shaft 502 is rotatable relative tothe sub-mirror balancer 500 even after the distal end of the contactshaft 502 has been crimped.

A torsion coil spring 500Sp is disposed over the shaft portion 501 ofthe sub-mirror balancer 500, the shaft portion 501 serving as therotation center of the sub-mirror balancer 500. A movable end of thetorsion coil spring 500Sp is held against on the lock pin 505 fixed tothe lock lever 504 that is rotatable about the contact shaft 502 as therotation center.

Thus, the sub-mirror lock lever 504 is biased by the spring force of thetorsion coil spring 500Sp.

The distal end of the contact shaft 502 is formed in a slotted shape(see e.g. FIG. 7). The angle of the sub-mirror 200 is adjusted byinserting a tool, such as a screwdriver, into a slot formed at thedistal end of the contact shaft 502, and by rotating the contact shaft502.

The operation of the balancer mechanism on the left side of thesub-mirror frame 200 a in FIG. 4 will be described below with referenceto FIGS. 7, 8A and 8B.

As described above, the torsion coil spring 500Sp is disposed over theshaft portion 501 serving as the rotation center of the sub-mirrorbalancer 500. A fixed end of the torsion coil spring 500Sp is heldagainst a fixed portion (not illustrated), and a movable end of thetorsion coil spring 500Sp is held against the lock pin 505 fixed to thelock lever 504.

The spring force of the torsion coil spring 500Sp is represented by aforce F in FIG. 7. Depending on a contact angle between the lock pin 505and the movable end of the torsion coil spring 500Sp, the force F isdecomposed to (resolved into) a component force F1 in a direction thatis perpendicular to the rotating direction of the sub-mirror lock lever504, and a component force F2 in a direction normal to the componentforce F1. The torsion coil spring 500Sp is set such that the componentforce F1 acting as a force to rotate the sub-mirror balancer 500 isgreater than the component force F2 acting as a force to rotate thesub-mirror lock lever 504, i.e., F1>F2.

The component force F1 provides a load when kinetic energy of thesub-mirror frame 200 a is transferred to the sub-mirror balancer 500.Thus, even when the inertia moment of the sub-mirror balancer 500 cannotbe set so large, the collision energy of the sub-mirror frame 200 a canbe absorbed by the load that is provided by the spring force of thetorsion coil spring 500Sp.

The component force F2 is the spring force imposed on the sub-mirrorlock lever 504. The component force F2 serves not only to provide a loadwhen the contact portion 201 of the sub-mirror frame 200 a is contactedwith the lock pin 505, but also to return the sub-mirror lock lever 504to a rebound regulation position when the contact portion 201 of thesub-mirror frame 200 a is rebounded from the contact shaft 502 afterriding over the lock pin 505.

FIG. 8A illustrates a state before the completion of the mirror-downoperation, i.e., a state immediately before the contact portion 201 ofthe sub-mirror frame 200 a is contacted with the lock pin 505. When thecontact portion 201 is contacted with the lock pin 505, the lock pin 505is rotated and thereafter the contact portion 201 is contacted with thecontact shaft 502.

Collision energy generated at that time is converted to energy forrotating the sub-mirror balancer 500, and the sub-mirror balancer 500 isrotated as illustrated in FIG. 8B. The lock pin 505 is also rotatedtogether with the sub-mirror balancer 500 such that the lock pin 505 canalways effectuate the rebound regulation when the contact portion 201 ofthe sub-mirror frame 200 a is rebound.

If the size of the sub-mirror balancer 500 is increased in its contourshape, a problem of interference with other components may occur. Inconsideration of such a problem, the sub-mirror balancer 500 is formedin a slender shape extending only in one direction from the shaftportion 501, which serves as the rotation center of the sub-mirrorbalancer 500, up to the adjustment portion 503. Thus, the contact shaft502 can effectively function as a balancer weight. In other words, anangle formed by the contact between the contact shaft 502 and thecontact portions 201 and the contact between the adjustment portion 503and the adjustment member 313 with respect to the rotation center of thesub-mirror balancer 500 is set to be not larger than 90° in oneembodiment.

When the sub-mirror 200 is displaced to the mirror-down state, thesub-mirror 200 is rotated in a direction in which it comes closer to animage pickup plane. Therefore, the sub-mirror balancers 500 and 510 arealso moved in a direction toward the image pickup plane. As illustratedin FIG. 1, the shutter device 12 is disposed closely in front of theimage pickup element 13. Hence, there is a risk that the sub-mirrorbalancers 500 and 510 may interfere with the shutter device 12 in thebalancing operations.

FIG. 9 is a front view of the shutter device 12. As illustrated in FIG.9, recesses 12 b and 12 c are formed in a plate, which is disposed onthe object side of the shutter device 12, thereby providing allowancesfor movements of the sub-mirror balancers 500 and 510. Such anarrangement can increase an amount of energy absorbed by the sub-mirrorbalancers 500 and 510, and can provide a satisfactory mechanism forabsorbing the bounce of the sub-mirror 200. The recesses 12 b and 12 cmay be in the form of holes, which also provide a similar beneficialeffect even when they are formed in continuation to an opening 12 a forphotographing.

FIGS. 10A to 10C are explanatory views illustrating the detailedstructure of the mirror box. FIG. 10A is a front perspective view of themirror box, and FIG. 10B is a rear perspective view of the mirror box.FIG. 10C is a rear perspective view illustrating a state where theshutter device 12, illustrated in FIG. 9, is mounted to the mirror box.

The mirror driving mechanism, illustrated in FIGS. 2A to 2C, is disposedat both sides of the mirror box, and a mirror charge mechanism 31 and amirror charge motor 30 are disposed at one side of the mirror drivingmechanism.

In this embodiment, when looking at the camera from the rear side, themirror charge mechanism 31 and the mirror charge motor 30 are disposedon the left side with respect to an optical axis, and the shutter device12 and a shutter charge motor 20 are disposed on the right side of theoptical axis.

Methods for adjusting the main mirror 100 and the sub-mirror 200 will bedescribed below.

Positioning of the rotation shafts 101 of the main mirror 100 is madesuch that the rotation shaft 101 on the left side is engaged in a holeformed in the base plate 300 of the mirror driving mechanism and therotation shaft 101 on the right side is fitted to an adjustment plate105 (see FIG. 10B). The position of the rotation shaft 101 of the mainmirror 100 on the right side can be adjusted by adjusting the positionof the adjustment plate 105.

In the above description, the angle of the main mirror 100 in therotating direction thereof is determined by the contact plate 103 of themain mirror 100 contacting with the contact shaft 402 and by the contactplate 104 of the main mirror 100 contacting with the contact shaft 412.More precisely speaking, however, the contact between the contact plate103 of the main mirror 100 and the contact shaft 402 and the contactbetween the contact plate 104 of the main mirror 100 and the contactshaft 412 do not occur at the same time.

In other words, when the main mirror 100 is displaced to the mirror-downstate, at the time either one of the contact between the contact plate103 of the main mirror 100 and the contact shaft 402 and the contactbetween the contact plate 104 of the main mirror 100 and the contactshaft 412 is established, the contact between the contact plate and thecontact shaft relating to the other contact is not yet established and agap still remains between them.

More specifically, a plane is determined by contacts at three points. Inthis embodiment, a plane of the main mirror 100 when the main mirror 100is displaced to the mirror-down state is determined by contacts at threepoints that are provided by two bearing portions bearing the rotationshafts 101 of the main mirror 100, and one of the contact shaft 402 andthe contact shaft 412.

In this embodiment, the contact plate 103 of the main mirror 100, whichis positioned on the left side where the adjustment of the position ofthe rotation shaft 101 of the main mirror 100 cannot be made, is broughtinto contact with the contact shaft 402 at earlier timing. Thereafter,the contact plate 104 of the main mirror 100, which is positioned on theright side where the adjustment of the position of the rotation shaft101 of the main mirror 100 can be made depending on the position of theadjustment plate 105, is brought into contact with the contact shaft412.

With such an arrangement, the angle of the main mirror 100 in therotating direction thereof can be adjusted on the basis of the sidewhere the rotation shaft 101 of the main mirror 100 is fixedly held. Ifthe angle of the main mirror 100 in the rotating direction thereof isadjusted on the basis of the side where the rotation shaft 101 of themain mirror 100 is movable, this implies that the angle of the mainmirror 100 in the rotating direction thereof is adjusted on the basis ofthe side including an error. Stated another way, an error related to theposition of the rotation shaft 101 of the main mirror 100 affects theangle of the main mirror 100 in the rotating direction thereof.

Similarly, in the above description, the angle of the sub-mirror 200 inthe rotating direction thereof is determined by the contact portion 201of the sub-mirror frame 200 a contacting with the contact shaft 502 andby the contact portion 202 of the sub-mirror frame 200 a contacting withthe contact shaft 512.

More precisely speaking, however, the contact between the contactportion 201 of the sub-mirror frame 200 a and the contact shaft 502 andthe contact between the contact portion 202 of the sub-mirror frame 200a and the contact shaft 512 do not occur at the same time. In otherwords, when the sub-mirror 200 is displaced to the mirror-down state, atthe time either one of the contact between the contact portion 201 ofthe sub-mirror frame 200 a and the contact shaft 502 and the contactbetween the contact portion 202 of the sub-mirror frame 200 a and thecontact shaft 512 is established, the contact between the contact plateand the contact shaft relating to the other contact is not yetestablished and a gap still remains between them.

In this embodiment, a plane of the sub-mirror 200 when the sub-mirror200 is displaced to the mirror-down state is determined by contacts atthree points that are provided by two bearing portions bearing therotation shaft of the sub-mirror 200, and one of the contact shaft 502and the contact shaft 512.

In this embodiment, the contact portion 202 of the sub-mirror frame 200a is contacted with the contact shaft 512, the contact portion 202 andthe contact shaft 512 being positioned on the right side of the mainmirror 100 where the angle of the main mirror 100 in the rotatingdirection thereof is not fixedly set. On the other hand, the contactportion 201 of the sub-mirror frame 200 a is not contacted with thecontact shaft 502, the contact portion 201 and the contact shaft 502being positioned on the left side of the main mirror 100 where the angleof the main mirror 100 in the rotating direction thereof is fixedly set.

Thus, in this embodiment, a mechanism for defining the plane of thesub-mirror 200 when the sub-mirror 200 is displaced to the mirror-downstate and a mechanism for defining the plane of the main mirror 100 whenthe main mirror 100 is displaced to the mirror-down state are positionedin a diagonal relationship.

During a period from a time when the main mirror 100 has come intocontact with the main mirror balancer 400 positioned on the left side toa time when the main mirror 100 comes into contact with the main mirrorbalancer 410 positioned on the right side, there occurs a force actingon the main mirror 100 to incline the same.

Similarly, during a period from a time when the sub-mirror 200 has comeinto contact with the sub-mirror balancer 510 positioned on the rightside to a time when the sub-mirror 200 comes into contact with thesub-mirror balancer 500 positioned on the left side, there occurs aforce acting on the sub-mirror 200 to incline the same. However, sincethe force acting on the main mirror 100 to incline the same and theforce acting on the sub-mirror 200 to incline the same are opposed toeach other in direction, the accuracy in positioning the main mirror 100and the sub-mirror 200 is improved.

Further, in this embodiment, the main mirror 100 first comes intocontact with the main mirror balancer 400 positioned on the left side,and then comes into contact with the main mirror balancer 410 positionedon the right side. On the other hand, the sub-mirror 200 first comesinto contact with the sub-mirror balancer 510 positioned on the rightside, and then comes into contact with the sub-mirror balancer 500positioned on the left side.

As a result, shocks generated when the main mirror 100 and thesub-mirror 200 are displaced to the mirror-down state can be distributedto the left side and the right side, and the shocks can be settled in ashorter time.

The present invention has been described in detail above in connectionwith the embodiment. The embodiment of the present invention has beendescribed in connection with a single-lens reflex digital camera, forexample, in which a lens is interchangeable, but the present inventioncan also be embodied in a structure that a camera body and a lens areintegral with each other and the lens is not interchangeable.

While the present invention has been described with reference to anexemplary embodiment, it is to be understood that the invention is notlimited to the disclosed exemplary embodiment. The scope of thefollowing claims is to be accorded the broadest interpretation so as toencompass all such modifications and equivalent structures andfunctions.

This application claims the benefit of Japanese Patent Application No.2011-086513 filed Apr. 8, 2011, which is hereby incorporated byreference herein in its entirety.

What is claimed is:
 1. A camera comprising: a mirror; a mirror contactmember with which the mirror is contactable; and a bounce regulationmember including a bounce regulation portion with which the mirror iscontacted when the mirror is bounced from the mirror contact member;wherein the mirror contact member is provided so as to be rotatablearound a rotation center, wherein the mirror contact member includes afirst eccentric portion that is eccentric with respect to the rotationcenter of the mirror contact member, and a second eccentric portion thatis eccentric with respect to the rotation center of the mirror contactmember substantially at the same eccentricity as that of the firsteccentric portion, wherein when the mirror is displaced to a mirror-downstate, the mirror is contacted with the first eccentric portion, andwherein the bounce regulation member is disposed to be rotatable aboutthe second eccentric portion.
 2. The camera according to claim 1,further comprising: a rotation member arranged to be rotated when themirror and the mirror contact member are contacted with each other,wherein the mirror contact member and the bounce regulation member areprovided on the rotation member.
 3. The camera according to claim 2,wherein the bounce regulation member is held between the mirror contactmember and the rotation member.
 4. The camera according to claim 2,further comprising: a biasing member arranged to bias the rotationmember, wherein the biasing member biases the rotation member in adirection opposed to a direction in which the rotation member is rotatedwhen the mirror and the mirror contact member are contacted with eachother, and wherein the biasing member biases the bounce regulationmember.